In many diagnostic and therapeutic medical applications (including drug delivery and analyte sampling/monitoring), precise transport of a drug, blood and/or other bio-fluid is important. However, with most conventional diagnostic and therapeutic medical systems, precise movement of large and small aqueous volumes of drugs and other bio-fluids is difficult to achieve. This difficulty arises because conventional systems employ mechanical components to effect fluid transport and delivery. Reconfiguration of these systems to enable highly precise movement of small and large aqueous volumes of a solution containing biomaterials would be impractical, as the complexity of such systems would make their manufacture expensive, time consuming and labor intensive.
Presently, electrokinetic (“EK”) or electro-osmotic manipulations of fluids represent the state-of-the art in controlled, high precision, small volume fluid transport and handling. Electro-osmosis involves the application of an electric potential to an electrolyte, in contact with a dielectric surface, to produce a net flow of the electrolyte.
While electro-osmosis has found widespread and wide ranging applications in chemical analysis (e.g., high-speed liquid chromatography and other chemical separation procedures), its medical applications, such as for drug delivery and analyte sampling, have been limited, despite its advantages over conventional, mechanical approaches. Design challenges, including accurately delivering a target flow rate over time, accumulation of charge on EK electrodes above a threshold value leading to pump fluid degradation (e.g., ˜±1.2 volts for water), and managing EK pump pressure, need to be overcome. When configured for non-medical use, these drawbacks do not pose major issues because the consequences are minimal, unlike in medical applications.
Accordingly, the present invention is directed to low-cost, high precision, reliable and compact EK pumps and systems adapted for medical applications, including, but not limited to, drug delivery and/or analyte sampling.